if(process.argv.length !== 3) {
    console.error('命令行格式：cmd base64_string');
    process.exit(1);
  }
  
  const buf = Buffer.from(process.argv[2], 'base64');
  const info = buf.toString('utf8').split(':');
  
  if(info.length !== 2) {
    console.error('信息有误！');
    process.exit(2);
  }
  
  console.log('user name: %s\npassword: %s', info[0], info[1]);
  